Buckmaster's Elements of animal physiology / by John Angell.

  • Angell, John
Date:
1866
Catalogue details

Licence: Public Domain Mark

Credit: Buckmaster's Elements of animal physiology / by John Angell. Source: Wellcome Collection.

    276/384 (page 264)
    Experiment I.—Place 21. weighed hono. in dilute muriatic acid; after some hours remove, wash, and again weigh it. It will be found to have lost about 2-3rds of its weight, and with it also to have lost its property of mjiexibility, and, if a long bone, may be twisted into a knot. The acid has dissolved out its earthy matter, consisting chiefly of tribasic phosphate of lime, and rendered it flexible. Experiment II.—Place a weighed haws, in a clear bright red fire, which does not smoke, for half an hour or more. When the bone is thoroughly burnt, and all traces of blackness have dis- appeared, remove carefully, allow it to cool slowly, and again weigh. It will be found to have lost i-3rd of its weight. Its animal or gelatinous constituent has been burnt away, and with it has disappeared its toughness. The hardness and inflexibihty of bone is dependent upon the mode of aggregation as well as upon the constituents of the bone, since certain very flexible fish bones contain tnore earthy matter than inflexible human bone. Bones in Infancy and Old Age.—The compo- sition of bones varies very much at different periods of life. In infancy the quantity of earthy matter in the bones is very small, being less than i-3rd of the weight of the bone. Properly speaking, true bone does not exist in the skeleton of an infant. In middle life the earthy matter constitutes about 2-3rds of the weight of the bone, while in advanced old age the quantity present in the bone is so great as to render it exceed- ingly brittle. The bones of an infant will bend and twist, but will not break. On the contrary, a very aged person can scarcely fall without breaking a bone; and when broken, in many cases the bone will not reunite. Bones are divisible, according to their shapes, into four classes—long, short, flat, and irregular. The Long Bones are found chiefly in the limbs, where they act as agents of support, locomotion, and prehension. A long bone consists of a shaft, or long cylindrical portion, and extremi- ties, which are generally expanded, the upper extremity termed \kilhead, and the lower extremity, which is generally expanded, the condyle. The shaft, or long cylindrical portion of the bone,